1. Field of the Invention
The present invention relates to soldering and desoldering devices, and more particularly, to a device that uses an improved pickup device for soldering or desoldering an item such as an electrical component.
2. Description of Related Art
It is commonly known to solder components together or to remove a component by desoldering. A common application is to solder (or mount) electrical components to a printed circuit board or to remove (or dismount) an electrical component by desoldering. The electrical components are usually soldered to the printed circuit board so that the electrical components are in an electrically conductive relationship with each other in order to form electrical circuits. The electrical components once soldered to the printed circuit board, also occasionally have to be removed from the printed circuit board, because of a defect therein or an incorrect arrangement, by melting the soldered portions and dismounting the electrical component from the printed circuit board.
A conventional method of dismounting an electrical component, such as an integrated circuit (IC) having a plurality of leads that are soldered to the corresponding conductive portions printed on the circuit board, comprises melting the solder at each of the leads with a soldering iron and picking out each lead with a pair of tweezers or the like one by one until the entire IC is completely removed from the board. This conventional method is disadvantageous in that because an IC has many soldered leads, considerable manual work is required to dismount the IC. Also, because the leads are short and fragile, the dismounting work is delicate and requires a great deal of skill. Mechanical damage to the body and leads of an IC is common and the heat involved in the melting of the solder by this laborious method may also adversely affect the functions of the IC or printed circuit board.
A more advanced method for installing or removing electrical components to or from a printed circuit board comprises an apparatus that includes a vacuum pickup device. The apparatus uses a vacuum tube with a suction cup on its end which can extend axially through the heating head of the apparatus to attach to the electrical component that is to be placed on or removed from the printed circuit board. The axial movement of the suction cup is controlled by the user via a manual turnable knob. The successful operation of this device depends to a certain extent on the user's correct operation of the turnable knob. For example, if the suction cup is lifted too early when attempting to remove a component, the solder will not have sufficiently liquefied and the component may be damaged, such as the leads being bent, or the suction cup may detach from the component. If the suction cup is lifted too late, the solder may have resolidified resulting similarly in component damage or suction cup detachment when the user attempts to remove the component. Additionally, the component may be damaged by the user pressing the suction cup and vacuum tube too hard against the component when attaching the suction cup to the component.
Various devices have been introduced in an attempt to eliminate these problems. These devices typically utilize a spring to assist the user in controlling the force applied to the suction cup. For example, one type of device has the vacuum pickup tube acted on by a spring in the direction toward the component to provide a resilient cushion against which the pickup tube can be displaced when contact is made with the component. This prevents the component from being damaged by too great a downward force applied by the user. However, this device can cause problems when attempting to install a component by applying too great a force to the component which results in defective solder connections due to leads splashing or passing through the solder incorrectly.
Another type of device has the vacuum pickup tube held in a raised position by a coil spring with the user lowering the pickup tube against the action of the spring until contact is made with the component. The vacuum then holds the suction cup to the component and the user can remove the applied pressure and concentrate on melting the solder. When the solder melts, the spring is applying the correct pressure and automatically lifts the component from the printed circuit board at the precise moment. However, this device is not effective for installing components because the spring is counterproductive to the user's efforts.
A third type of device attempts to combine the features of the above-mentioned two devices, by incorporating the spring from each device. The vacuum pickup tube is clamped to a slide bracket that slides on a slide rod fixed to an inner wall of the device. The slide bracket is positioned between two springs disposed around the slide rod and centered within a rack member that has teeth that engage a gear wheel that rotates when the user turns the external vacuum pickup adjustment knob. The springs position the suction cup of the vacuum pickup device in a neutral position in an attempt to achieve the advantages of the prior two devices. When attaching the suction cup to a component, additional force by the user after component engagement results in compression of one of the springs. After attaching the suction cup to the component for dismounting, the user can apply upward spring loading to the other spring by turning the adjustment knob so that when the solder is melted the spring automatically lifts the component from the printed circuit board. However, this device has many small parts that make it difficult to assemble, manufacture, and repair. Furthermore, design shortcomings and numerous moving parts make it difficult to operate.
Accordingly, it would be desirable to provide a soldering and desoldering device that incorporates a vacuum pickup device that assists the user in engaging mounted components for removal or in positioning and installing components. The device may be handheld or stationary and allows a user to properly engage components or dismount a component by automatically lifting the component once the solder has melted. Furthermore, the device would be easy to assemble, manufacture, and repair and would be easy to use and operate.